Feeding device for sewing machines



Jan. 5, 1943. c. A. KESSLER FEEDING DEVICE FOR 'SEWINGMACHINE'S Fil ed Oct. 8, 194;

Patented Jan. 5, 1943 UNITED STATES PATENT OFFICE FEEDING DEVICE FOR SEWING MACHINES Application October 8,

6 Claims.

This invention relates to sewing machines and more particularly to the feeding mechanism of such machines.

The feeding of a fragile, open mesh or similar fabric has always been recognized by those skilled in the sewing machine art as a difficult operation. This difliculty arises mainly because, in the feeding of such fabrics, the widely spaced cross-threads thereof are caught by the teeth of the conventional feed-dog and thereby broken.

Therefore, to overcome this trouble, feed-dogs have been constructed with relatively short teeth so that the cross threads would not be caught so readily between the teeth. Although this expedient obviated a great part of the above noted difliculty, the life of the feed-dog was shortened considerably as it required very little time for the short teeth to be worn away, thus applying a substantially smooth and consequently ineffective feeding surface to the work. A smooth feed-dog surface is an inefficient feeding medium for the reason that the conventional feed-dog is formed of a hardened steel and thus presents a work-engaging surface which, when its short teeth wear out, becomes polished and has a very small coefficient of friction.

One of the objects of this invention therefore, is the provision of a feeding element which will facilitate the feeding of lace or fragile open mesh fabrics, and at the same time constitute a simple and rugged device having a relatively long life.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawing of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

The several features of the present invention will be clearly understood from the following description and accompanying drawing in which:

Fig. l is an end elevation of a sewing machine having my invention embodied therein.

Fig. 2 is a perspective view showing a conventional feed-bar and my improved feed-dog mounted thereon.

Fig. 3 is a fragmentary view, partly in section, 1 the feed-bar with the improved feed-dog mounted thereon' Fig. 4 is a fragmentary View of a vertical section of the present feed-dog.

In the embodiment of this invention selected for illustration, Ill represents the bed-plate of a 1941, Serial No. 414,049

conventional type sewing machine having the hollow head ll. Journaled in suitable bearings carried by the hollow head II is a needle-bar l2 carrying a needle l3 which cooperates in the usual manner in the formation of stitches with the loop-taker element l4 suitably carried by the sewing machine base l5. Also carried by the hollow head H is the presser-bar l6 carrying a presser-foot ll which is urged downwardly by the usual spring means (not shown).

Journaled in the machine base I is the feed advance and return rock-shaft I8, and the feedlift rock-shaft 19, both of which cooperate in the usual manner to impart feed-and-return and rising-and-falling movements to the feed-bar 20. The base member 22 of the feed-dog is secured by means of screws 2| to the feed-bar 20, and the feeding surface of the feed-dog cooperates with the presser-foot I! to advance the material through the machine. For a more detailed description of the above described feeding mechanism reference may be had to the patent to Diehl et al., No. 1,146,406, dated July 13, 1915.

It is understood that although the above deto illustrate my presentinvention, any other conventional feeding mechanism would have been equally appropriate.

Projecting from the body portion 23 of the hardened feed-dog are teeth 24 provided with pointed crown portions 25 which, in the form herein illustrated, lie in a single plane. The teeth 24 are preferably formed of hardened steel.

Bonded or otherwise secured to and disposed between the hardened teeth of each parallel row of teeth 24, is a filler or covering material 26 formed of any suitable unhardened substance. In the preferred form of the present invention commercial solder is used as the filler material, but it is to be understood that a suitable nonmetallic substance such as cork, rubber, or the like could also be utilized depending upon the surrounding working conditions. The feeding or Work-engaging surface of the present feed-dog material '26.

By using a filler material, such as above described, in the present type of feed-dog, the crossthreadS of a fabric are prevented from being caught between the feed-dog teeth. It is also to be understood that such a filler material has an inherently greater coefficient of friction than does the hardened steel teeth and therefore, said material enhances the feeding characteristics of scribed type of feeding mechanism is herein used therefore includes the crown portions 25 of the teeth 24 and the exposed portions of the filler,

the dog. Furthermore, by using such a relatively soft filler material it has been found that as the teeth Wear away the filler will also wear away or be packed downwardly so that the crowns of the teeth will always be partially exposed. It will be understood therefore, that normal life of the feed-dog is not shortened by the addition of the filler.

It is obvious that minor changes in the details of construction may be made without departing from the spirit of the invention as set forth in the appended claims.

Having thus set forth the nature of the invention what I claim herein is:

1. A sewing machine feed-dog comprising, a body portion, a plurality of hardened metallic teeth projecting from said body portion, and an unhardened filler material bonded to said teeth, said teeth being covered by said filler material so that only the crowns thereof protrude above the level of said filler material.

2. A feeding element for sewing machines comprising, a body portion, an unhardened covering material carried by one surface of said body portion, and a plurality of hardened teeth embedded in said covering material.

3. A sewing machine feeding element having a body portion and a feeding suriace provided on said body portion, said feeding surface comprising areas of hardened teeth, and areas of unhardened covering material.

4. A feeding element for sewing machines comprising, a body portion, a plurality of hardened steel teeth projecting from said body portion, and a filler material composed of solder bonded to and surrounding said teeth so that only the crowns thereof protrude above the solder.

5. A sewing machine feeding device comprising, a, body portion, a covering of unhardened and unpolished material carried at one side of said body portion, and a plurality of hardened teeth embedded in said covering material, said unhardened covering material having a greater coefiicient of friction than that of said teeth.

6. A feed-dog for sewing machines comprising, a body portion, a plurality of parallel rows of hardened teeth projecting from said body portion, the crowns of said teeth defining a single plane, and an unhardened filler material bonded to and disposed between the hardened teeth of each parallel row of teeth, the exposed surface area of said unhardened material being greater than that of said hardened teeth.

CHARLES A. KESSLER. 

